A detailed study of the mass spectrometry of the explosives RDX and HMX has resulted in a detailed knowledge of their fragmentation reactions under various ionization conditions. Selective reaction monitoring has been demonstrated to be a useful technique for the confirmation of 2,3,7,8-TCDD in air filter samples. The analysis of Firemaster FF-1 for minor and suspected toxic impurities has been accomplished using HRGC-HRMS.